Question

A small telescope has an objective of focal length 140 cm and an eye piece of focal length 5.0 cm. The magnifying power of telescope for viewing a distant object is :

• A. 34
• B. 28
• C. 17
• D. 32

Answer 1

The Correct Option is B

Step 1: Recall the Formula for Magnifying Power

The magnifying power (M) of a telescope for a distant object is given by:

$$ M = \frac{f_o}{f_e} $$

Where:

\( M \) = Magnifying power

\( f_o \) = Focal length of the objective lens

\( f_e \) = Focal length of the eyepiece

Step 2: Substitute the Given Values

Given:

• \( f_o = 140 \) cm
• \( f_e = 5.0 \) cm

Substituting the values:

$$ M = \frac{140}{5} = 28 $$

Step 3: Conclusion

The magnifying power of the telescope is 28.